There are approximately 250,000 new cases of breast cancer diagnosed each year in the US [1
]. Improved screening and treatment methods have increased the breast cancer survival rate such that the majority of women with localized, early stage disease can expect to live many years after a diagnosis of breast cancer. Thus, in addition to continuing to strive to improve detection and survival rates, more work is needed on issues that influence the quality of breast cancer survivors' lives. One important factor is appearance change as a result of surgical treatment for breast cancer.
Breast reconstructive surgery is an important component to improve the patient's quality of life. Approximately 57,000 breast reconstructive surgeries are performed annually in the US, according to the American Society of Plastic Surgeons [2
]. The goal of breast reconstruction is to recreate a breast form that is satisfying to the patient, facilitating her psychosocial adjustment to living as a breast cancer survivor. Currently, physicians, patients, or other observers evaluate characteristics of the reconstructed breasts, such as symmetry and proportion, in a subjective, qualitative manner [3
]. However, such assessments are typically based on vaguely defined rating scales that have low intra- and inter-observer agreement. Their qualitative nature also restricts the analyses that can be performed. Current quantitative approaches to breast esthetic measurements include: measurements on the patient's body (anthropometry) [4
], measurements on 2D [6
] or 3D [10
] imaging. Anthropometry can be a useful tool for quantifying esthetic outcomes. However, this method can be complicated and time intensive, making it impractical for routine use. Using photographs has advantages over anthropometry. A photograph is more efficient and less intrusive for the patient because it serves a stable record for a variety of measurements. However, this method also suffered from substantial intra- and inter-observer variability, due to the lack of consistency in the manual identification of anatomic landmarks [12
]. Three-dimensional imaging has tremendous potential for analysis of breast appearance. However, it is not routinely collected in clinics due to the high cost.
Quantitative, objective measures are needed to enable outcomes research. Understanding how different kinds of observers perceive reconstruction and developing of tools for quantifying breast morphology could impact breast cancer care in a variety of ways. In the future, such measures may also be used directly in surgical planning. Another possible application is in surgical education. In addition to laying the groundwork for assisting surgeons in performing better reconstructions, such advances would enable the development of patient decision aids. Another use is in setting appropriate reimbursement rates for different procedures. To the best of our knowledge, there are no prior studies that substantively investigate the relationships between specific surgical variables reliably and psychosocial adjustment. In fact, this lack of detailed understanding of the psychological consequences of reconstructive procedures motivates our overall research agenda on relating changes in breast morphology to the perceptions of cancer survivors and caregivers. However, in developing quantitative, objective measures that capture critical aspects of breast appearance, it would be helpful to understand how people subjectively evaluate breast morphology.
The goal of this investigation is to explore the potential of eye-tracking technology for elucidating the process of subjective assessment of breast reconstruction surgery outcomes on 2D images. In this pilot study, we record the gaze path of three plastic surgeons while he or she rates breast characteristics based on clinical photographs. Eye tracking is a valuable tool for understanding medical image perception. For example, eye tracking has been used in numerous studies on the visual search processes of radiologists. Eye tracking has enabled scientists to study factors such as the effect of lesion conspicuity on the visual search strategy of radiologists' in mammogram reading [13
], the relationship between duration of gaze at lesion and correct diagnosis of it [14
], the relationship between lesion subtlety and detection of the lesion [15
], and to predict radiologists' diagnosis using spatial frequency representation of regions [16
]. Eye tracking has also been used in some studies to investigate how body-image assessment is related to preferential attention toward the body part. For example, eye tracking was used to investigate how age and fatigue judgments are made using the facial cues as participants viewed full-face digital photographs [17
] and to investigate the visual assessments by men of female attractiveness who viewed computer-morphed anterior–posterior (AP) photographs of the woman with same face, but differ for waist to hip ratio [18
]. In comparison, there have been few studies employing eye tracking in the field of plastic and reconstructive surgery. For example, Ishii et al. reported statistically significant differences in the patterns of scan paths of eight naive observers when gazing at images of faces with vs. without surgical deformities [19
]. Moreover, we are unaware of any previous studies in breast reconstructive surgery that employed eye-tracking technology. Thus, there is a clear opportunity to introduce this powerful methodology to a new clinical research area where we can evaluate and reengineer the current methods used to assess breast reconstructive surgery.